1. Field
The invention relates to a transfer gripper for a rapier weaving loom having yarn clamps for keeping in readiness a piece or length of a weft yarn to be taken over by a receiving gripper and extending between yarn clamps.
2. Related Art
In modern rapier weaving looms, the transfer grippers, located on a rapier band or rapier rod, are moved at very high speeds. They must be braked down from this high speed when they reach the transfer point where a receiving gripper takes over the weft yarn. Because of its inertia, it can happen that the weft yarn moves onward, so that the piece of yarn to be taken over by the receiving gripper moves away from its specified position. It can then happen that the receiving gripper will not grasp the weft yarn, causing a weft fault. The risk that the piece of yarn to be taken over will come loose can also occur, especially with heavy weft yarns, even if a properly functioning yarn brake is provided on the insertion side, since the forces of inertia stretch the weft yarn elastically downstream of the yarn brake.
A piece of yarn to be taken over by a receiving gripper is prevented from coming loose if this piece is held between two yarn clamps (British patent specification GB 14 87 897). In this kind of construction, two identical yarn clamps are provided, which are loaded by the same spring element. The piece of yarn located between the two yarn clamps and meant to be taken over by the receiving gripper will not move out of range of the specified position even upon braking down from high speeds. The receiving gripper has a hooklike head with which it must reach behind the piece of yarn that is held between the two yarn clamps. In the process, the hooklike head deflects the piece of yarn, which then moves backward behind the hook when the hooklike head is moved past that piece of yarn. This deflection, if the weft yarns are not very elastic and/or have only relatively low strength, can cause the piece of yarn to become damaged or destroyed, so that the piece cannot be grasped then, and a weft fault occurs.